docs: def _set_default_refdata():
      """Default refdata set on import."""
      global GRAPHTABLE, COMPTABLE, THERMTABLE, PRIMARY_AREA
      # Component tables are defined here.
  
      try:
          GRAPHTABLE = _refTable(os.path.join('mtab','*_tmg.fits'))
          COMPTABLE  = _refTable(os.path.join('mtab','*_tmc.fits'))
      except IOError as e:
          GRAPHTABLE = None
          COMPTABLE = None
          warnings.warn('No graph or component tables found; '
                        'functionality will be SEVERELY crippled. ' + str(e))
  
      try:
          THERMTABLE = _refTable(os.path.join('mtab','*_tmt.fits'))
      except IOError as e:
          THERMTABLE = None
          warnings.warn('No thermal tables found, '
                        'no thermal calculations can be performed. ' + str(e))
  
      PRIMARY_AREA = 45238.93416  # cm^2 - default to HST mirror
  
      set_default_waveset()